The most important piece of advice I can give is to surround yourself as much as possible with the language. We live in Maine and we do not have the opportunity to practice outside of class so we have to actively seek out opportunities. Here is a tip from the author of the blog Fluent in 3 Months

...create a very amusing, animated, unforgettable image in your mind that links both words to each other! This means that if you are translating either to or from the target language (unlike just from which most people will master easier), you will access the other word just as easily. This is especially important when the words look nothing alike...

ex: el tobillo-ankle

Picture a small dog named Toby nipping at your ankles as you walk down a hallway.